Panning is a complex confectionery or pharmaceutical operation which until recently was more of an art than a science. Simply stated, panning is the repetitive crystallization of sucrose or other sugar or syrup-like coating on a tumbling mass of centers. Thin crystal layers build upon each other to form the resulting shell or coating. The coating syrup can be applied hot for centers capable of withstanding elevated temperatures, i.e., jawbreakers, or cold for centers, i.e., chocolate or chewing gum. Coating solutions can be prepared by simply dissolving sucrose in water and using a refractometer to measure the percentage of solids concentration or brix.
The selection of syrup temperature and concentration is determined by the desired product quality and thickness of the coating. For example, if the center will not readily melt, and the coating is relatively thick, a high concentration of 75-85% at 140.degree. F. (60.degree. C.) can be used. Syrup solids will range from 85% concentration for hot panning applications to 65% concentration for finish coatings. Normal syrup solids and application temperatures are 75-77% at 140.degree. F./60.degree. C. for hot panning, 69-72% at 80.degree./27.degree. C. for cold panning, and 65-67% at 80.degree. F./27.degree. C. for finishing. The higher the concentration, the faster the drying time and the larger the crystals. Conversely, a lower solids concentration, as in finishing syrup, results in increased drying time and smaller, finer crystals.
Hard sugar panning is a somewhat slow and tedious process because only one thin coat of crystals can be applied at a time, and each coat must be thoroughly dried before the following application is applied. Too quick of an application will cause coating failure and processing problems. Production times can be reduced somewhat by using higher concentration syrups during initial coating processes and then gradually reducing the syrup concentration so that the finished surface is coated with small fine crystals. Care must be taken though in early coatings so as not to create a "rough" center that is impossible to finish to a smooth shell. For high quality products, patience is required and the process is inevitably slow.
After finishing, the product is normally stored in trays overnight in a conditioned storage area for drying prior to polishing. This is not always required and the length of drying time will depend upon the syrup application rate and concentration of solids.
Polishing is usually accomplished in a ribbed pan by the application of dry or liquid carnauba/bee's wax blends. For additional product protection, confectioner's glazes can also be applied to the waxed pieces. Normally, confectioner's glazed products should be "aired" in well ventilated trays for 18-24 hours prior to packaging to allow any solvents to evaporate.
As can be seen from the above description, panning can be a long, expensive, tedious and imperfect process. With the availability of high technology sensors, monitors and other technologies, the "art" or "feel" of traditional confectionery panning can now be eliminated.
One attempt to do so can be found in U.S. Pat. No. 4,639,383 issued to Casey. Casey discloses a method and apparatus for coating particulate granules. The method is practiced by providing a fluidized charge of granules suspended in a flow of a drying gas within a rotating perforated coating pan. The coating material is dispersed onto the moving granules suspended in the flow of drying gas. The use of panning techniques involving suspending the granules in a fluidized bed produced by a current of air, may be desirable to speed the drying of the individual granules, but such techniques present their own problems.
For example, the suspension of the granules creates vigorous agitation of the granules since they are in constant movement in the air flow. Such vigorous agitation increases collisions between granules, resulting in damage to the product and excessive dust formation within the pan. Also, in the use of such techniques as in Casey, coating material is wasted as some of it is inevitably lost in the exhaust of the flow of drying gas. Further, the dispersion of drying gas or air during the coating operation can dry the product too fast, not allowing the product to become adequately or evenly saturated. Additionally, the plumbing requirements for such systems often require complicated plumbing structures and configuration.
The present invention solves the problems of conventional panning techniques as well as the problems in fluidizing techniques such as Casey. The invention provides a relatively fast, controlled, and efficient panning process by the repetition of separate spray, distribution, and drying cycles.